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BUG/MINOR: haproxy: only tid 0 must not sleep if got signal

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This patch fixes the commit eea152ee68
("BUG/MINOR: signals/poller: ensure wakeup from signals").

There is some probability that run_poll_loop() becomes inifinite, if
TH_FL_SLEEPING is withdrawn from all threads in the second signal_queue_len
check, when a signal has received just after the first one.

In such particular case, the 'wake' variable, which is used to terminate
thread's poll loop is never reset to 0. So, we never enter to the "stopping"
part of the run_poll_loop() and threads, except the one with id 0 (tid 0
handles signals), will continue to call _do_poll() eternally and will never
sleep, as its TH_FL_SLEEPING flag was unset.

This flag needs to be removed only for the tid 0, as it was done in the first
signal_queue_len check.

This fixes an issue #2537 "infinite loop when shutting down".

This fix must be backported in every stable version.
This commit is contained in:
Valentine Krasnobaeva 2024-05-06 14:24:41 +02:00 committed by Willy Tarreau
parent 03ca16f38b
commit 4a9e3e102e
1 changed files with 1 additions and 1 deletions
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2
src/haproxy.c
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@ -3087,7 +3087,7 @@ void run_poll_loop()
if (thread_has_tasks()) {
activity[tid].wake_tasks++;
_HA_ATOMIC_AND(&th_ctx->flags, ~TH_FL_SLEEPING);
} else if (signal_queue_len) {
} else if (signal_queue_len && tid == 0) {
/* this check is required after setting TH_FL_SLEEPING to avoid
* a race with wakeup on signals using wake_threads() */
_HA_ATOMIC_AND(&th_ctx->flags, ~TH_FL_SLEEPING);